private void btnGenerate_Click(object sender, EventArgs e)
        {
            double monthlyfee;

            // Existence checks
            if (txtMonthlyFee.Text.Trim() == string.Empty)
            {
                MessageBox.Show("Enter Monthly Fee", Text, MessageBoxButtons.OK, MessageBoxIcon.Information);

                txtMonthlyFee.Focus();
                return;
            }

            //Type Check
            if (double.TryParse(txtMonthlyFee.Text, out monthlyfee) == false)
            {
                MessageBox.Show("Enter a number for Fee.", Text, MessageBoxButtons.OK, MessageBoxIcon.Information);

                txtMonthlyFee.Focus();
                return;
            }


            else // All checks are satisfied
            {
                InvoiceReceipt InvoicePayment = new InvoiceReceipt();

                InvoicePayment.SetSubscriberID((int)NUDSubID.Value);
                InvoicePayment.SetMonthlyFee(double.Parse(txtMonthlyFee.Text));
                InvoicePayment.SetRenewalDate(DTPRenewalDate.Value);

                lstInvoice.Items.Add(lstInvoiceFetch(InvoicePayment));
                SendStatusUpdate(true, "Records Generated!", "success");
            }
        }
        private ListViewItem lstInvoiceFetch(InvoiceReceipt xInvoice)
        {
            ListViewItem lstInvoice = new ListViewItem(xInvoice.GetSubscriberID().ToString());

            lstInvoice.SubItems.Add(xInvoice.GetMonthlyBill().ToString());
            lstInvoice.SubItems.Add(xInvoice.GetRenewalDate().ToLongDateString());

            return(lstInvoice);
        }